Dental prosthesis

ABSTRACT

A dental prosthesis comprising an implant, an abutment attached to the implant in a manner wherein an implant abutment joint is defined therebetween, and a crown attached to the abutment and the implant in a manner wherein the implant abutment joint is covered by the crown. The attachment of the crown to the abutment and the implant is accomplished through the use of an adhesive which extends between the crown and the implant in a manner wherein the adhesive seals the implant abutment joint thereby preventing any bacterial colonization or other deterioration therein.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. applicationSer. No. 08/679,223 entitled DENTAL PROSTHESIS filed Jul. 12, 1996, nowabandoned, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to dental prostheses and, moreparticularly, to a dental prosthesis including an implant, an abutmentwhich is attached to the implant, and a crown which is attached to boththe abutment and the implant such that the joint defined between theabutment and the implant is covered and affectively sealed by aprosthetic margin of the crown.

BACKGROUND OF THE INVENTION

As is well known in the prior art, dental prostheses are commonly usedin the dental field to address extensive damage to teeth caused byinjury or disease. A typical dental prosthesis comprises an implant, anabutment, and a crown. The implant itself generally comprises a metalliccomponent which is implanted or embedded into the bony structure of apatient's mouth subsequent to the removal of the damaged tooth or teethalone or in combination with one or more adjacent teeth. Theinstallation of the implant is typically accomplished by preparing ahole in the bony structure and screwing threads formed on the implantinto the hole. After the implant has been embedded into the bonystructure, the bone normally recovers and grows around the implant, thusresulting in bone/implant integration. To enhance the integration of thebone thereto, the implant may be coated with a biocompatible coatingsuch as hydroxylapatite.

Subsequent to the embedding of the implant into the bony structure, theabutment is attached to the implant. Such attachment may be accomplishedthrough the use of a cement, the engagement of complementary male andfemale threads formed on or in the abutment and implant, or the matingof corresponding tapers or other geometries formed on or in the abutmentand implant. When attached to the implant, a portion of the abutmentextends above the gum line of the patient for purposes of allowing theattachment of the crown thereto. If the implant is embedded in the bonystructure such that the same is completely disposed below or submergedwithin the gum line of the patient, the attachment of the abutment tothe implant requires a second surgical procedure for purposes ofaccessing the implant. However, if the implant is embedded in the bonystructure in a manner wherein a portion thereof protrudes above thepatients gum line, then the attachment of the abutment thereto may beaccomplished without the need for the second surgical procedure, thusrequiring only the initial surgical procedure to complete theimplantation or embedding process.

As previously indicated, the crown of the dental prosthesis is attachedto that portion of the abutment which extends above the patient's gumline. In the prior art, crowns are fabricated and installed inaccordance with well-established procedures which include taking atransfer impression of the exposed portion of the abutment to establishwith precision its configuration and orientation, thus insuring acomplete attachment of the crown thereto. The exposed portion of theabutment to which the crown is attached may have the natural form of aprepared tooth, or an artificial form of a particular geometry adaptedto achieve a secure attachment of the crown thereto. The attachment ofthe crown to the abutment is typically accomplished through the use of acement, or through the engagement of corresponding male and femalethreads on or in the crown and abutment to each other. The attachment ofthe crown to the abutment completes the assembly of the dentalprosthesis.

As will be recognized from the aforementioned description of the dentalprosthesis, the assembly thereof results in the formation of severaldistinct joints. These joints include the joint formed by the attachmentof the crown to the abutment, and the joint formed by the attachment ofthe abutment to the implant. Of these joints, that joint considered mostimportant in relation to the long-term viability of the prosthesis isthe joint between the implant and the abutment which is commonlyreferred to as the implant abutment joint or "IAJ".

Recent research in the dental field has suggested that the IAJ plays akey role in bone loss around the implant. Though such bone loss has notbeen well studied or well documented, it is believed by the dentalprofession to be a common occurrence which is at least partiallyattributable to the IAJ serving as a site for bacterial invasion andcolonization. Over time, such bone loss can compromise the implant orcause its failure by breaking loose from the bony structure in which itis implanted or embedded. Obviously, such failure, in addition toproviding inconvenience and discomfort for the patient, is of seriousmedical concern due to the resulting bone loss or mutilation potentiallyrendering the installation of a replacement implant difficult orimpossible. The joint formed by the attachment of the crown to theabutment is also susceptible to bacterial invasion which contributes tobone loss around the implant. The present invention addresses thesusceptibility of the IAJ and the crown/abutment joint to bacterialinfestation by providing a dental prosthesis which is configured toeffectively cover and seal these joints.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a dentalprosthesis which comprises an implant adapted to be embedded into thebony structure of a patient's mouth. The dental prosthesis furthercomprises an abutment which is attached to the implant in a mannerwherein an abutment joint is defined therebetween. In addition to theimplant and the abutment, the dental prosthesis comprises a crown whichis attached to the abutment and to the implant in a manner wherein theimplant abutment joint is covered by the crown. The attachment of thecrown to the abutment and the implant is accomplished through the use ofan adhesive which extends between the crown and the implant in a mannerwherein the adhesive seals the implant abutment joint and the jointformed between the crown and the implant. In this respect, the adhesiveeffectively isolates these joints from the gum line of the patient toprevent any migration of bacteria thereto.

In the preferred embodiment, the implant itself includes an elongate,externally threaded implant distal portion which is insertable into thebony structure of the patient's mouth, and an implant proximal portionwhich itself includes distal and proximal segments. The distal segmentof the implant proximal portion has a generally cylindrical outersurface, with the proximal segment having a beveled or tapered outersurface in one embodiment of the present invention, and a generallycylindrical outer surface of a lesser diameter than the outer surface ofthe distal segment in another embodiment of the present invention. Theproximal segment defines an implant proximal end of the implant.Extending axially within the implant proximal end is an implant aperturewhich has a generally circular cross-sectional configuration.

The abutment of the dental prosthesis includes an abutment proximalportion which has a generally frusto-conical outer surface. As such, thegeneral shape of the abutment proximal portion is that of a truncatedcone. Extending axially from the end of the abutment proximal portion ofgreater diameter is a cylindrically configured, shaft-like abutmentdistal portion of the abutment. The attachment of the abutment to theimplant is facilitated by the slidable insertion of the abutment distalportion into the implant aperture. The advancement of the abutmentdistal portion into the implant aperture is limited by the engagement ofthe abutment proximal portion to the implant proximal end. In oneembodiment of the present invention, the abutment distal portion issecured within the implant aperture through the use of an adhesive. Inanother embodiment of the present invention, the implant aperture isinternally threaded, with the abutment distal portion being externallythreaded and the attachment of the abutment to the implant beingfacilitated by the threadable receipt of the abutment distal portioninto the implant aperture.

The crown of the present dental prosthesis includes a crown distalportion which defines a crown distal end having a crown aperturedisposed therein. The crown aperture has a shape which is complementaryto the outer surface of the abutment proximal portion and the outersurface of the proximal segment of the implant proximal portion when theabutment is attached to the implant. In this respect, the receipt of theabutment proximal portion and the proximal segment of the implantproximal portion into the crown aperture results in the engagement ofthe crown distal portion to the proximal segment of the implant proximalportion (i.e., the direct contact therebetween) and the covering of theimplant abutment joint defined between the abutment proximal portion andthe implant proximal end by the crown distal portion. The adhesive usedto secure the crown to the abutment and the implant flows or extendsbetween the crown distal portion and the tapered outer surface of theproximal segment of the implant proximal portion, thus effectivelysealing the joint between the crown and the implant, and hence theimplant abutment joint as well as the joint between the crown and theabutment.

In the embodiment of the implant wherein the proximal segment of theimplant proximal portion has the tapered outer surface, the attachmentof the abutment to the implant in the above-described manner results inthe sloped outer surface of the abutment proximal portion beingsubstantially continuous or flush with the tapered outer surface of theproximal segment. In that embodiment of the implant wherein the proximalsegment of the implant proximal portion has the generally cylindricalouter surface, the attachment of the abutment to the implant in theabove-described manner results in the sloped outer surface of theabutment proximal portion extending at a slight angle relative to thecylindrical outer surface of the proximal segment. In accordance with afurther embodiment of the present invention, the abutment may have atwo-piece construction wherein the abutment distal portion is defined bya shaft member of the abutment, and the abutment proximal portion iscollectively defined by the shaft member and a generally frusto-conicalsleeve member of the abutment which is attached to the shaft memberthereof.

Further in accordance with the present invention, there is provided amethod of installing a dental prosthesis into a patient which comprisesthe initial step drilling a hole into the bony structure of thepatient's mouth or oral cavity, and thereafter threading an implant ofthe dental prosthesis into the hole. An abutment of the dentalprosthesis is then attached to the implant in a manner wherein animplant abutment joint is defined between the abutment and the implant.Thereafter, a layer of adhesive is applied to exposed portions of boththe abutment and the implant. A crown is then attached to the adhesivecovered portions of the abutment and the implant in a manner wherein theimplant abutment joint is covered by the crown. The attachment of thecrown to the abutment and the implant results in the flow or extensionof the adhesive between the crown and the implant in a manner whereinthe adhesive seals the implant abutment joint and the joint between thecrown and the implant. The step of attaching the abutment to the implantmay be accomplished through the use of an adhesive, or via thethreadable engagement of the abutment to the implant.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a exploded view of a dental prosthesis constructed inaccordance with a first embodiment of the present invention,illustrating the implant, abutment, and crown thereof;

FIG. 2 is a perspective view of the dental prosthesis of the firstembodiment in an assembled state;

FIG. 3 is a cross-sectional view of the dental prosthesis of the firstembodiment in its assembled state as shown in FIG. 2;

FIG. 4 is a partial cross-sectional view of the dental prosthesis of thefirst embodiment in its assembled state as shown in FIG. 2;

FIG. 5 is a partial cross-sectional view of a dental prosthesis of asecond embodiment of the present invention in an assembled state;

FIG. 6 is a partial cross-sectional view of a dental prosthesis of athird embodiment of the present invention in an assembled state;

FIG. 7 is a partial cross-sectional view of a dental prosthesis of afourth embodiment of the present invention in an assembled state;

FIG. 8 is a partial cross-sectional view of a dental prosthesis of afifth embodiment of the present invention in an assembled state; and

FIG. 9 is a partial cross-sectional view of a dental prosthesis of asixth embodiment of the present invention in an assembled state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred embodiments of the present invention only, andnot for purposes of limiting the same, FIGS. 1-4 depict a dentalprosthesis 10 constructed in accordance with a first embodiment of thepresent invention. The dental prosthesis 10 comprises an implant 20which is adapted to be embedded into the bony structure of a patient'smouth or oral cavity. The implant 20 itself includes an elongate implantdistal portion 22 which defines an implant distal end 30 and includesexternal threads 28 formed thereon. The implant distal portion 22 isinsertable into the bony structure of the patient's mouth, and moreparticularly is threaded into a hole drilled into the bony structure aswill be described in more detail below.

In addition to the implant distal portion 22, the implant 20 includes animplant proximal portion 24. The implant proximal portion itselfincludes a distal segment 34 which has a generally cylindrical outersurface, and a proximal segment 36 which, in the first embodiment, has abeveled or tapered outer surface. The proximal segment 36 also definesan implant proximal end 37. The distal and proximal segments 34, 36 ofthe implant proximal portion 24 meet at a prosthetic margin 70, with theproximal segment 36 extending radially inward at a slight angle relativeto the distal segment 34. The outer diameter of the distal segment 34slightly exceeds the maximum outer diameter of the implant distalportion 22, thus resulting in the formation of an annular shoulder 26therebetween. Disposed within the implant proximal end 37 is an implantaperture 32 which has a generally circular cross-sectionalconfiguration, and extends axially through the implant proximal portion24 to approximately the mid-point of the implant distal portion 22, asseen in FIG. 3.

In the first embodiment, the implant 20 is fabricated from a metallic,biocompatible material such as titanium. Additionally, the implantdistal portion 22 may be coated with hydroxylapatite or other suitablebiocompatible material to assist in the integration of the implant 20 tothe bony structure of the patient's mouth. Additionally, the implantdistal portion 22 may be etched with a suitable acid or other solution.

In addition to the implant 20, the dental prosthesis 10 of the firstembodiment includes an abutment 40 which is attached to the implant 20in a manner which will be described in more detail below. The abutment40 comprises a cylindrically configured, shaft-like abutment distalportion 41 and an abutment proximal portion 43 which has a generallyfrusto-conical outer surface. As such, the abutment proximal portion 43has the basic shape of a truncated cone. In the dental prosthesis 10,the abutment distal portion 41 is sized such that the outer diameterthereof is slightly less than the diameter of the implant aperture 32.The abutment 40 is also preferably fabricated from a metallic,biocompatible material, such as titanium.

In the dental prosthesis 10, the attachment of the abutment 40 to theimplant 20 is facilitated by the slidable insertion of the abutmentdistal portion 41 into the implant aperture 32. As will be recognized,the advancement of the abutment distal portion 41 into the implantaperture 32 is terminated by the engagement of the abutment proximalportion 43 to the implant proximal end 37 (i.e., the direct contacttherebetween). Importantly, the engagement of the abutment proximalportion 43 to the implant proximal end 37 results in the formation of animplant abutment joint 72 between the abutment 40 and the implant 20.

As seen in FIGS. 3 and 4, the length of the abutment distal portion 41is such that when the abutment 40 is fully inserted into the implant 20(i.e., the implant abutment joint 72 is formed), the abutment distal end42 of the abutment 40 terminates short of the closed bottom end of theimplant aperture 32. In this respect, in the dental prosthesis 10 of thefirst embodiment, the abutment distal portion 41 is secured within theimplant aperture 32 through the use of an adhesive. The adhesive may beapplied to the abutment distal portion 41 prior to its advancement intothe implant aperture 32 and/or injected into the implant aperture 32prior to the insertion of the abutment distal portion 41 thereinto. Thegap defined between the abutment distal end 42 and the closed bottom endof the implant aperture 32 provides an area for adhesive to accumulateand harden, therefore strengthening the bond between the abutment 40 andthe implant 20. As further seen in FIGS. 3 and 4, due to the sloped ortapered configurations of the outer surfaces of the proximal segment 36of the implant proximal portion 24 and outer surface of the abutmentproximal portion 43, when the abutment 40 is attached to the implant 22in the above-described manner, such outer surfaces extend in a generallycontinuous or flush relation to each other.

The dental prosthesis 10 of the first embodiment further comprises acrown 60 which is fabricated from an inert biocompatible material suchas ceramic or metal or both, and is configured in a desired exteriorsurface configuration in a manner known in the art. The crown 60includes a crown distal portion 61 which defines a crown distal end 64.Disposed within the crown distal end 64 is a chamfered hole 66 whichtransitions into a blind hole 62. The chamfered and blind holes 66, 62collectively define a crown aperture of the crown 60. As further seen inFIGS. 3 and 4, the configuration of the crown aperture, and inparticular the chamfered hole 66 partially defining the same, results inthe crown distal end 64 having an annular, knife-edge configuration.Additionally, as will be discussed in more detail below, the blind hole62 is adapted to receive the abutment proximal portion 43 and thereforehas a shape which is complementary thereto, with the chamfered hole 66being adapted to receive the proximal segment 36 of the implant proximalportion 24, and therefore having a shape which is complementary thereto.

In the dental prosthesis 10, the crown is attached to the abutmentproximal portion 43 of the abutment 40, and to the proximal segment 36of the implant proximal portion 24 of the implant 20. Such attachment isaccomplished through the use of an adhesive which is applied to theouter surface of the abutment proximal portion 43 including the abutmentproximal end 44 defined thereby, and to the outer surface of theproximal segment 36 of the implant proximal portion 24. The crown 60 isthen advanced over the abutment 40 and implant 20 such that the abutmentproximal portion 43 is snugly received into the blind hole 62 and theproximal segment 36 of the implant proximal portion 24 is snuglyreceived into the chamfered hole 66. The advancement of the crown 60over the abutment 40 and implant 20 is limited by the engagement of theabutment proximal end 44 against the closed bottom end of the blind hole62. Importantly, the crown 60 is formed such that when the abutmentproximal portion 43 is fully received into the blind hole 62 and theproximal segment 36 fully received into the chamfered hole 66, theknife-edge crown distal end 64 extends to and terminates at theprosthetic margin 70 defined between the distal and proximal segments34, 36 of the implant proximal portion 24.

When the crown 60 is attached to the abutment 40 and implant 20 in theabove-described manner, the crown distal end 64, by virtue of itsextension to the prosthetic margin 70, is distal to the implant abutmentjoint 72, thus resulting in the crown distal portion 61 completelycovering the implant abutment joint 72. Additionally, the adhesive usedto attach the crown 60 to the abutment proximal portion 43 and proximalsegment 36 of the implant proximal portion 24 extends and is disposedbetween the outer surface of the proximal segment 36 and the innersurface of the crown distal portion 61 which defines the chamfered hole66. Importantly, the curing or hardening of this adhesive effectivelyseals the implant abutment joint 72, therefore completely isolating thesame from the deteriorous effects of bacterial invasion, plaque anddisease. The cured or hardened adhesive also prevents bacterialmigration between the crown 60 and implant 20 by sealing the jointbetween the crown distal portion 61 and proximal segment 36 of theimplant proximal portion 24. Also sealed by the cured adhesive is thejoint between the crown 60 and the abutment proximal portion 43. Thus,the adhesive serves several essential purposes which include theattachment of the crown 60 to the abutment 40 and implant 20, andsealing off the implant abutment joint 72 and joint between the crown 60and implant 20 for purposes of preventing the creation of any site(s) inthe dental prosthesis 10 which are susceptible to bacterial invasion.

Referring now to FIG. 5, there is depicted a dental prosthesis 110constructed in accordance with a second embodiment of the presentinvention. The dental prosthesis 110 includes an implant 120 which issubstantially similar to the previously described implant 20, andincludes an implant distal portion 122 and an implant proximal portion124 which are separated by an annular shoulder 126 defined therebetween.The implant proximal portion 124 itself includes a distal segment 134which, like the previously described distal segment 34, has a generallycylindrical outer surface.

In addition to the distal segment 134, the implant proximal portion 124includes a proximal segment 136 which has a tapered outer surface.However, in contrast to the dental prosthesis 10, the transition betweenthe distal and proximal segments 134, 136 in the dental prosthesis 110is defined by a curved or arcuate region 137. Forming this arcuateregion 137 in the implant 120 allows the distal end 164 of the crown 160of the dental prosthesis 110 to be rounded and formed with greaterthickness, and avoids the knife-edge configuration of the crown distalend 64 in the dental prosthesis 10 of the first embodiment which is moresusceptible to breakage or other damage. This alternative configurationfor the crown distal end 164 is particularly desirable for crowns madeof a ceramic material, in that the previously described knife-edgeconfiguration is generally considered most acceptable for crowns made ofgold or other malleable material. The attachment of the crown 160 to theabutment 140 and implant 120 is accomplished in the same manner aspreviously described in relation to the dental prosthesis 10, therebyresulting in the crown 160 effectively covering the implant abutmentjoint 172 defined between the abutment 140 and the implant 120.

Referring now to FIG. 6, there is depicted a dental prosthesis 210constructed in accordance with a third embodiment of the presentinvention. The dental prosthesis 210 includes an implant 220 which issubstantially similar to the previously described implant 20, andincludes an implant distal portion 222 and an implant proximal portion224 which are separated by an annular shoulder 226 defined therebetween.The implant proximal portion 224 itself includes a distal segment 234which, like the previously described distal segment 34, has a generallycylindrical outer surface.

In addition to the distal segment 234, the implant proximal portion 224includes a proximal segment 236 which also has a generally cylindricalouter surface. However, the diameter of the outer surface of theproximal segment 236 is substantially less than the diameter of theouter surface of the distal segment 234. As such, in contrast to thedental prosthesis 10, the transition between the distal and proximalsegments 234, 236 in the dental prosthesis 210 is defined by an annularshoulder 237. Forming this shoulder 237 in the implant 220 allows thedistal end 234 of the crown 260 of the dental prosthesis 210 to besquared off and formed with greater thickness, thus avoiding theknife-edge configuration of the crown distal end 64 in the dentalprosthesis 10 of the first embodiment which is more susceptible tobreakage or other damage. This alternative configuration for the crowndistal end 264 is also desirable for crowns made of a ceramic material.The attachment of the crown 260 to the abutment 240 and implant 220 isaccomplished in the same manner as previously described in relation tothe dental prosthesis 10, thereby resulting in the crown 260 effectivelycovering the implant abutment joint 272 defined between the abutment 240and the implant 220.

Referring now to FIG. 7, there is depicted a dental prosthesis 310constructed in accordance with a fourth embodiment of the presentinvention. The dental prosthesis 310 includes an implant 320 which issubstantially similar to the previously described implant 20, anddiffers only in that the slope of the tapered outer surface of theproximal segment 336 of the implant proximal portion 324 issubstantially greater than that of the outer surface of the proximalsegment 36 of the implant proximal portion 24. Such increased sloperesults in the length of the distal segment 334 of the implant proximalportion 324 exceeding that of the distal segment 34 of the implantproximal portion 24 in the dental prosthesis 10. The attachment of thecrown 360 in the dental prosthesis 310 to the implant 320 thereof stillresults in the crown distal end 364 extending distally beyond theimplant abutment joint 372, and the crown 360 thus effectively coveringthe implant abutment joint 372 when adhesively attached to the abutment340 and implant 320.

Referring now to FIG. 8, there is depicted a dental prosthesis 410constructed in accordance with a fifth embodiment of the presentinvention. The dental prosthesis 410 is substantially similar to thepreviously described dental prosthesis 10. However, in the dentalprosthesis 410, the abutment distal portion 441 of the abutment 440 isexternally threaded, with the abutment proximal portion 443 including arecess disposed within the abutment proximal end for receiving ascrewdriver or other implement to rotate the abutment 440. Additionally,the implant aperture 432 of the implant 420 is internally threaded. Assuch, the attachment of the abutment 440 to the implant 420 isaccomplished by the threadable receipt of the abutment distal portion441 into the implant aperture 432. In the dental prosthesis 410, theattachment of the crown 460 to the abutment 440 and implant 420 resultsin the crown distal end 464 extending distally beyond the implantabutment joint 472, and the crown 460 covering the implant abutmentjoint 472 when adhesively attached to the abutment 440 and implant 420.

Referring now to FIG. 9, there is depicted a dental prosthesis 510constructed in accordance with a sixth embodiment of the presentinvention. The dental prosthesis 510 is substantially similar to thepreviously described dental prosthesis 410, except that the abutment 540of the dental prosthesis 510 is provided with a two-piece construction.More particularly, the abutment 540 comprises a shaft member 553, aportion of which is externally threaded. In addition to the shaft member553, the abutment 540 includes a sleeve member 551 which has a generallyfrusto-conical outer surface. The abutment 540 is formed by theattachment of the sleeve member 551 to the shaft member 553. Theexternally threaded portion of the shaft member 553 defines the abutmentdistal portion 541 of the abutment 540 which is threadably received intothe internally threaded implant aperture 532 of the implant 520. Thenon-threaded portion of the shaft member 553 and sleeve member 551collectively define the abutment proximal portion 543 of the abutment540. The top of the shaft member 553 partially defining the abutmentproximal portion 543 includes a recess therein for receiving ascrewdriver or other implement to rotate the abutment 540 as is neededto accomplish the threadable engagement thereof to the implant 520. Theattachment of the crown 560 of the dental prosthesis 510 to the abutment540 and implant 520 results in the crown distal end 564 extendingdistally beyond the implant abutment joint 572, and hence the crown 560covering the implant abutment joint 572 when adhesively attached to theabutment 540 and implant 520.

Having thus described preferred embodiments of dental prosthesesconstructed in accordance with the present invention, the method ofinstalling the dental prosthesis 10 of the first embodiment into apatient's mouth or oral cavity will now be described. However, those ofordinary skill in the art will recognize that this installation processis equally applicable to the additional embodiments of the dentalprosthesis described above.

The dental prosthesis 10 is used by initially drilling a hole into thebony structure of the patient's mouth or oral cavity. Thereafter, theexternally threaded implant distal portion 22 of the implant 20 isembedded into the bony structure by threading the same into the holepreviously drilled therein. The implant 20 is preferably embedded intothe bony structure in a manner wherein the proximal segment 36 of theimplant proximal portion 24 thereof protrudes above the bony structureof the patient's mouth. However, the proximal segment 36 may be disposedbelow, at, or above the patient's gum line.

Subsequent to the embedding of the implant 20 into the bony structure,the abutment 40 is rigidly attached to the implant 20 in theabove-described manner. As indicated above, the attachment of theabutment 40 to the implant 20 may be accomplished through the use of anadhesive, or via the threadable engagement of the abutment 40 andimplant 20 to each other.

After the abutment 40 has been attached to the implant 20, a transfercast is made of the exposed portions of the abutment 40 and implant 20.As will be recognized, these exposed portions include the tapered outersurface of the proximal segment 36 of the implant proximal portion 24,and the frusto-conical outer surface of the abutment proximal portion 43of the abutment 40. This transfer cast is used to fabricate the crown 60of the dental prosthesis 10 to insure the complete covering of theexposed portions of the abutment 40 and implant 20 thereby.

Subsequent to the fabrication of the crown, a layer of adhesive isapplied to the exposed portions of the abutment 40 and the implant 20(i.e., the outer surface of the abutment proximal portion 43 and theouter surface of the proximal segment 36). The crown 60 of the dentalprosthesis 10 is then attached to those portions of the abutment 40 andthe implant 20 which are covered by the adhesive. Such attachmentresults in the implant abutment joint 72 being completely covered by thecrown distal portion 61 of the crown 60, and the extension or flow ofthe adhesive between the inner surface of the crown distal portion 61defining the chamfered hole 66 and the tapered outer surface of theproximal segment 36 of the implant proximal portion 24. The adhesivealso extends between the inner surface of the crown 60 defining theblind hole 62 and the outer surface of the abutment proximal portion 43.The curing of the adhesive seals the implant abutment joint 72, thejoint formed between the crown 60 and implant 20 (i.e., between thecrown distal portion 61 and the outer surface of the proximal segment 36of the implant proximal portion 24), and the joint formed between thecrown 60 and abutment 40 (i.e., between the crown 60 and the outersurface of the abutment proximal portion 43).

In the present invention, the covering of the implant abutment jointwith the crown and the sealing of the implant abutment joint, the jointbetween the crown and the implant, and the joint between the crown andthe abutment by the adhesive eliminates the susceptibility of suchjoints to bacterial invasion, plaque contamination or otherdeteriorations. This results in a number of benefits to the patient. Inthis respect, bone loss is lessened or eliminated at the implant sincedisease is unable to thrive in or around these joints. As second majorbenefit is the anti-rotation of the connection of the crown to theimplant achieved by the curing of the adhesive therebetween.

Additional modifications and improvements of the present invention mayalso be apparent to those of ordinary skill in the art. Thus, theparticular combination of parts described and illustrated herein isintended to represent only certain embodiments of the present invention,and is not intended to serve as limitations of alternative deviceswithin the spirit and scope of the invention.

What is claimed is:
 1. A dental prosthesis, comprising:an implant; anabutment attached to the implant in a manner wherein an implant abutmentjoint is defined therebetween; and a crown attached to the abutment andthe implant in a manner wherein the implant abutment joint is covered bythe crown;the attachment of the crown to the abutment and the implantbeing accomplished through the use of an adhesive which extends betweenthe crown and the implant in a manner wherein the adhesive seals theimplant abutment joint.
 2. The dental prosthesis of claim 1 wherein:theimplant includes an implant distal portion and an implant proximalportion which defines an implant proximal end having an implant aperturedisposed therein; the abutment includes an abutment proximal portion andan abutment distal portion which is inserted into the implant apertureto facilitate the attachment of the abutment to the implant; and thecrown includes a crown distal portion which defines a crown distal endhaving a crown aperture disposed therein;the receipt of the abutmentproximal portion into the crown aperture resulting in the engagement ofthe crown distal portion to the implant proximal portion and thecovering of the implant abutment joint by the crown distal portion. 3.The dental prosthesis of claim 2 wherein the abutment proximal portionhas a generally frusto-conical outer surface.
 4. The dental prosthesisof claim 3 wherein:the implant proximal portion includes a distalsegment and a proximal segment having a tapered outer surface which issubstantially continuous with the outer surface of the abutment proximalportion when the abutment is attached to the implant; and the crownaperture has a shape which is complementary to the outer surface of theabutment proximal portion and the outer surface of the proximal segmentwhen the abutment is attached to the implant;the receipt of the abutmentproximal portion and the proximal segment into the crown apertureresulting in the engagement of the crown distal portion to the outersurface of the proximal segment, the covering of the implant abutmentjoint by the crown distal portion, and the sealing of the implantabutment joint by the adhesive extending between the crown distalportion and the outer surface of the proximal segment.
 5. The dentalprosthesis of claim 3 wherein:the implant proximal portion includes adistal segment and a proximal segment having a generally cylindricalouter surface which extends at an angle relative to the outer surface ofthe abutment proximal portion when the abutment is attached to theimplant; and the crown aperture has a shape which is complementary tothe outer surface of the abutment proximal portion and the outer surfaceof the proximal segment when the abutment is attached to the implant;thereceipt of the abutment proximal portion and the proximal segment intothe crown aperture resulting in the engagement of the crown distalportion to the outer surface of the proximal segment, the covering ofthe implant abutment joint by the crown distal portion, and the sealingof the implant abutment joint by the adhesive extending between thecrown distal portion and the outer surface of the proximal segment. 6.The dental prosthesis of claim 2 wherein the abutment distal portion issecured within the implant aperture through the use of an adhesive. 7.The dental prosthesis of claim 2 wherein:the implant aperture isinternally threaded; the abutment distal portion is externally threaded;and the attachment of the abutment to the implant is facilitated by thethreadable receipt of the abutment distal portion into the implantaperture.
 8. The dental prosthesis of claim 2 wherein the implant distalportion is externally threaded.
 9. The dental prosthesis of claim 2wherein the abutment comprises:a shaft member; and a sleeve memberattached to the shaft member;the abutment distal portion being definedby the shaft member and the abutment proximal portion being collectivelydefined by the shaft member and the sleeve member.
 10. The dentalprosthesis of claim 9 wherein the shaft member is partially externallythreaded.
 11. The dental prosthesis of claim 9 wherein the sleeve memberhas a generally frusto-conical outer surface.
 12. A method of installinga dental prosthesis into a bony structure of a patient's oral cavity,the method comprising the steps of:(a) drilling a hole into the bonystructure; (b) embedding an implant of the dental prosthesis into thehole; (c) attaching an abutment of the dental prosthesis to the embeddedimplant in a manner wherein an implant abutment joint is definedtherebetween; (d) applying a layer of adhesive to exposed portions ofthe abutment and the implant; and (e) attaching a crown of the dentalprosthesis to those portions of the abutment and the implant covered bythe adhesive in a manner wherein the implant abutment joint is coveredby the crown and the adhesive extends between the crown and the implantto seal the implant abutment joint.
 13. The method of claim 12 whereinstep (b) comprises threading the implant into the hole in the bonystructure.
 14. The method of claim 12 wherein step (c) comprisesadhesively securing the abutment to the implant.
 15. The method of claim12 wherein step (c) comprises threadably engaging the abutment to theimplant.
 16. The method of claim 12 wherein:step (d) comprises making atransfer cast of the exposed portions of the abutment and the implantprior to the application of the layer of adhesive thereto; and step (e)comprises fabricating the crown from the transfer cast to insure thecomplete covering of the adhesive covered portions of the abutment andthe implant thereby.